Re: [PATCH 2/3] ext4: Implement subtree ID support for ext4 filesystem

On Wed, 11 Jul 2012 09:24:29 -0400, Theodore Ts'o [off-list ref] wrote:

On Wed, Jul 11, 2012 at 04:59:24PM +0400, Dmitry Monakhov wrote:

quoted

May be it would be better if i describe feature as "Namespace ID"
namespaces is well known abstraction in kernel, so misunderstanding
shouldn't happen.

What if we call it a "quota group", with the rules that if a parent
directory has a quota group, any files or directories created in that
parent directory will inherit that quota group, and only processes
with CAP_SYS_ADMIN can change it.

And then what if we simply make the rule that if an inode has a quota
group, the quota is charged against two group id's; the group id named
in inode, and the quota group?

Yes this looks reasonable, the only thing that we should aware of is id
collision. We have to reserve pool numbers to quota group id's.
This can be easily solved by changing disk structure of quota-file
to use u64 on uid.

That is, do we really need to have a separate namespace for group ids
and "subtrees" or "namespaces"?  That means we don't have to change
the userspace quota tools and we can leverage the existing ways people
are used to managing group quotas.

						- Ted
--

P.S. You probably heard about tragedy in Krimsk due to water flood.
Tonight i'll go Krimsk to help as a volunteer, so i probably will be
out of Internet next 10-12days. Please excuse me, i'll send updated
version right after i'll back to Moscow.

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